1. Field of the Invention
The present invention relates to an image recording apparatus which records an image by transporting a sheet-shaped recording medium and discharging an ink or inks onto the transported recording medium, and a control method for controlling the image recording apparatus.
2. Description of the Related Art
The image recording apparatus has been hitherto provided, for example, by printers, copying machines, and multifunction machines having the printing, scanning, copying, and facsimile functions.
Such an image recording apparatus includes an apparatus based on the so-called ink jet recording system provided with a placing section on which a sheet-shaped recording medium such as the recording paper or the like is placed, a feed roller which feeds the recording medium from the placing section, a first driving motor which drives the feed roller, a main transport roller pair which interposes and transports the recording medium fed by the feed roller, a second driving motor which drives the main transport roller pair, a recording head which records an image by discharging an ink or inks onto the recording medium transported by the main transport roller pair, and a control unit which controls the ink discharge to be performed by the recording head, the driving of the first driving motor, and the driving of the second driving motor. The image recording apparatus based on the ink-jet recording system is provided with, for example, a detecting section such as an encoder or the like in which the output is changed depending on the rotation amount of the main transport roller pair. The control unit described above performs the line feed by judging the feed amount of the recording medium fed from the main transport roller pair in accordance with the change of the output of the encoder.
Another image recording apparatus is known, in which a plurality of driving sections such as a feed roller and the like are driven by one driving motor by using a driving force transmitting/switching mechanism.
Still another image recording apparatus is known, in which a placing section is accommodated in a lower portion of a casing, a recording head is arranged over or above the placing section, and a curved section is provided at a transport passage for transporting a recording medium in order to realize a compact size.
The image recording apparatus can be made compact by providing the curved section at the transport passage. However, the recording medium, which is transported, receives the frictional force at the curved section. Therefore, if the radius of curvature of the curved section is too small, then the frictional force is excessively increased, and the relationship between the output change of the encoder described above and the feed amount of the recording medium from the main transport roller pair is disordered. The position accuracy of the image recording is lowered.